Many boards send you your password by e-mail, f.ex if you forgot it, as a service..
usually they also tell you that the first thing you should do is
change it ! ..
.. over SSL (HTTPS) of course

and you shouldn't be using the same password for multiple accounts because there
are punks who try to steal passwords and/or crack accounts, God knows why ...
By default EVERYTHING you send over the internet is in clear-text
and can be read by anyone with access to the wires, that's just how networking was designed ..
E-mails are like a postcard, all you need to read them is access .
You can use GPG
http://www.gnupg.org/to encrypt your E-mail but it requires that sender and receiver both have it installed
and it requires key-management,passphrases etc etc ..
Theres a GPG-extension for Thunderbird available,
it works very well and is relatively simple to set up
https://addons.mozilla.org/en-US/thunderbird/addon/71Use a password-manager like KeePass
http://keepass.info/ it also has a password-generator,that way you can have unique log-ins for each account
and only need to remember one master-password .
Your log-ins are stored in a 256bit AES encrypted database .